Processing plants typically include a series of operations in which liquid, gas, and solid materials are transported, heated, mixed, chemically treated, cooled, pressurized or otherwise processed. The different processes may be classified into the following types: flow, level pressure, temperature, mechanical, or analytical.
Each of such operations must generally be monitored and controlled to ensure that it is being properly performed according to some predetermined specifications or criteria. This monitoring and controlling typically requires instrumentation consisting of gauges or sensors to sense a present condition, a transmitter for transmitting the sensed data, a computer or other decision maker that receives the sensed data and decides whether an adjustment is needed, wiring or junction boxes to connect the components, and a valve that responds to the computer to make the adjustment. Alarms are also desirable in some situations to warn of high and low conditions.
Each of these sensor-transmitter-computer-valve combinations is called an instrument "loop". A typical petrochemical process plant may have hundreds of instrument loops.
A loop may be classified by the type of process it controls (flow, level, pressure, etc.) and also by the classes of components used in the loop. Some component types include electronic, pneumatic, and mechanical.
Loops may also be classified by the location of the decision-making computer. A "board" loop is one where the transmitter sends the sensed data to a central control computer or board. A "local" loop is one where a local sensor or field transmitter sends a control signal to a local controller and field valve, without computer intervention. A "local panel" loop is one that sends the signal to a local or field control board unit instead of to a centralized computer.
There are also many different types of components that may be used in such loops. For example, there may be a different transmitter type for each type of process (e.g. flow transmitters, level transmitters, etc.) In addition, each component type has subtypes with differing specifications or manufacturers.
From the above discussion, it is apparent that there are literally thousands of different combinations of loop and component types that may be used in a process plant.
In the past, a unique loop drawing or template was designed and hand-drawn for each loop used in a process plant, requiring many man-hours of work and taking long periods of time. The engineer studied the overall process plant flow diagram (P&ID), chose the instrument loop, and for each loop decided which components were necessary in the loop, specified each component separately on an instrument index, and then hand-drew the loop with its components by referencing the instrument index. The loop drawings were then filed or stored for later use.
The advent of Computer-Aided Design (CAD) programs expedited the creation of the loop drawings by enabling the operator to instruct the computer, using a digitizer or mouse, where to place the components and lines on the drawing, and having the computer transfer the component symbols from a symbol library onto the drawing.
Even with a CAD program, however, a unique template must be drawn for each loop, each drawing must be designed by a human designer, a human operator must manipulate the computer to generate a CAD template, and each template must be stored for later use. Many man-hours are still required to generate a loop drawing even when CAD programs are used. After the loop drawing has been created, the text that is to appear on the loop drawing is then transferred onto it.
It is therefore desirable to decrease the number of man-hours required to design and draw the loop drawings for a process plant instrumentation system. The present invention accomplishes this objective.
As discussed above, every general type of loop component (e.g., transmitter, valve, etc.) has many component subtypes (e.g., flow valve, pressure valve), which in turn have many different specifications and manufacturers. There are hundreds or thousands of distinct components that may be used in a process plant. Each of these components has a number of different specifications or other information associated with it, such as temperature ratings, pressure ratings, frequencies, manufacturer's name, model numbers, materials, etc.
In the past, each such piece of information or specification associated with a loop component had to be separately input into a database. Each time a new component was specified, the information had to be input even if the same information had already been input for another component (e.g., materials; manufacturer's name; certain specifications). This inputting was typically performed by a human operator typing at a keyboard. This inputting task is partially redundant, consumes many man-hours of typing at a high labor coast, is inefficient, and causes delays.
It is therefore desirable to decrease the amount of component information that must be input by a human operator. The present invention accomplishes this result as well.